What this calculator does
This Final Grade Calculator works in two modes. In "Final Exam Grade I Need" mode it tells you the score you must earn on the final exam to reach a target overall course grade. In "Final Class Grade" mode it tells you the overall course grade you will end with once you know the score you actually got on the final. Both modes use a weighted average and work with any percentage-based grading system, so it applies to high school, college, and university courses everywhere.
How to use it
Pick a mode from the "Find:" dropdown. Enter your current grade (your weighted average on everything before the final) and the final exam weight (the percent of the total course grade the final counts for). Then enter either the grade you want (mode 1) or the grade you scored on the final (mode 2). The result updates instantly.
The formula explained
Let \(w\) = final exam weight ÷ 100, \(C\) = current grade, \(G\) = target/overall grade, and \(F\) = final exam grade. The current grade covers the remaining \(1 - w\) share of the course.
To find the grade needed on the final: $$F = \frac{G - \left(1 - w\right)\cdot C}{w}$$
To find the overall grade: $$G = \left(1 - w\right)\cdot C + w\cdot F$$ These two formulas are exact inverses of each other.
Worked example
Current grade \(C = 88\%\), target \(G = 85\%\), final weight = 30%, so \(w = 0.30\). Then $$\left(1 - 0.30\right) \times 88 = 61.6$$ and \(85 - 61.6 = 23.4\), and \(23.4 \div 0.30 = \mathbf{78\%}\). You need 78% on the final. Checking the inverse: $$\left(0.70 \times 88\right) + \left(0.30 \times 78\right) = 61.6 + 23.4 = 85\%$$ your target.
FAQ
Why does it say I need over 100%? Your target is not reachable with the final's current weight. The tool shows the maximum course grade you can still achieve if you score 100% on the final.
Why is the grade needed negative? Your target is already locked in — even a 0% on the final would still meet your goal.
What if the final exam weight is 0%? The final cannot change your grade, so a "grade needed" is undefined. Set a weight greater than 0%.
